This thesis reports the results of a randomised controlled intervention study carried out between May and November 1993 in a major public hospital in the metropolitan area of Fortaleza City, Ceará, Brazil. The objective was to investigate the impact of post abortion counselling on uptake of contraception and on subsequent pregnancy and abortion. The study population was a sample of women hospitalised with complications of induced abortion which were identified during as larger hospital-based study on abortion. The intervention was half an hour of contraceptive counselling prior to discharge at the study site hospital. No contraceptive method was given. A total of 695 women were enrolled into the study, 345 in the intervention group and 350 in the control group. They were followed up at home at 2 weeks, 6 weeks, 4 months, 8 months and 1 year after discharge. Data were collected by trained interviewers using a structured questionnaire. Outcome measures of interest were; knowledge of contraceptive methods, seeking contraceptive services, uptake of contraception, having unprotected sexual intercourse, subsequent pregnancies and subsequent abortion. The study results show that this particular mode of counselling (single shot hospital-based post-abortion) increased the level of knowledge of some contraceptive methods, but did not have any effect in changing behaviour such as seeking contraceptive services, uptake of contraception or having unprotected sexual relationship. As a consequence, counselling did not show any impact on preventing another unwanted pregnancy and induced abortion. Among 695 women, 165 (23.7%) became pregnant again before the end of the 1 year follow-up; 81 (23.5%) in the intervention group and 84 (24.0%) in the control group. Of the 695 women, 42 (6.0%) had another abortion before the end of the 1 year follow-up; 27 (7.8%) in the intervention group and 15 (4.3%) in the control group. At 6 weeks visit, of the 662 women interviewed, 345 (52.1%) were using contraceptive methods; 178 (53.8%) in the intervention group and 167 (50.5%) in the control group. Women who were not using contraception after abortion tended to be young, single or without a partner. "Not having sexual intercourse" was the most frequently cited reason for not using a contraceptive method during the follow-up period. Suggestions were made on how a more effective intervention that might prove more successful in responding to these women' s needs for enhanced contraception can be developed.

Pregnancy-mediated sodium (Na) retention is required to provide an increase in plasma volume for the growing fetus. The mechanisms responsible for this Na retention are not clear. In the first study, we generated a renal tubule protein profile indicating α ENaC as the only sodium transport protein upregulated in mid and late pregnancy. To determine the in vivo activity of ENaC we conducted in vivo studies in late pregnant rats (day 18-20) and virgin rats to measure the natriuretic response to ENaC blockade (with benzamil). The in vivo activity of ENaC (UNaV post benzamil - UNaV post vehicle) was markedly increased in late pregnancy and this difference was abolished by pretreatment with the mineralocorticoid receptor antagonist, eplerenone. These findings demonstrate that the increased α ENaC subunit of pregnancy is associated with a mineralocorticoid-dependent increase in ENaC activity. The plasma volume increased progressively during pregnancy with the greatest plasma volume being evident in late pregnancy. ENaC inhibition abolished the difference in plasma volume status between virgin and pregnant rats. This indicates ENaC activity is a major contributor of plasma volume status in late pregnancy. Inadequate plasma volume expansion results in complicated pregnancy with growth restricted (GR) fetus and maternal/fetal death. The second study aimed to determine the importance of renal vs extrarenal ENaC in sodium retention and blood pressure regulation during pregnancy to do so we chronically blocked ENaC with either daily subcutaneous injections of benzamil (BZ) or intrarenal transfection of αENaC shRNA. Chronic ENaC blockade with benzamil prevented normal sodium retention in the pregnant rat. Prevention of sodium retention resulted in reduced maternal serum sodium concentration, blood pressure, body weight, and fetal growth restriction. However, chronic benzamil treatment had no effect on sodium retention, body weight, or BP in virgin rats. Intrarenal transfection of a shRNA targeting αENaC successfully decreased renal αENaC mRNA expression in late pregnant rats compared to controls transfected with scrambled sRNA. Intrarenal transfection of αENaC shRNA reduced sodium retention maternal, ΔBW, and pup weight. These findings suggest that renal ENaC is necessary for maintenance of sodium balance, blood pressure regulation, and progression of a healthy pregnancy. In the third study, we performed large-scale proteomic analysis on late pregnant and virgin principal collecting duct cells, isolated by laser capture microscopy. The primary aim of this project was to identify potential proteins or signaling pathways that could account for the sodium retention occurring in pregnancy. Large-scale liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed at the NIH which identified a total of 365 proteins in virgin and late pregnant collecting duct cells. We identified pregnancy associated abundance changes in six proteins related to the ubiquitin/proteasome degradation pathway. Since a major mechanism of ENaC regulation is through trafficking we focused on changes in this pathway and their implications for enhancing ENaC activity during pregnancy. The final study aimed to apply these findings to the overall theme of pregnancy as a state of arterial underfilling. We performed a Na transporter profile in kidney cortex homogenates from animals treated chronically with vasodilators (nifidipine or sodium nitrate). We found that only the abundance of transporters in the distal nephron (NCC, ENaC, AQP2) was similar to pregnancy, however differences were seen in pre-macula densa transporters (NHE3, NKCC2). The similar changes observed in the distal convoluted tubule and renal collecting duct promote Na and water retention. The changes in these transporters may explain the similar plasma volume expansions previously described in pregnant and chronically vasodilated rats, thus supporting the underfill hypothesis of pregnancy. Taken together, this project supports an important role for the collecting duct in the pregnancy mediated sodium and fluid reabsorption during pregnancy.

Obesity is recognized as a risk factor for adverse pregnancy outcomes. Maternal obesity prevalence has increased in parallel with that in the general population and is associated with an increase in morbidity and mortality for both mother and baby. Obese mothers are more likely to develop gestational diabetes, hypertensive disorders including preeclampsia, thromboembolic complications, miscarriage, and have an increased need for induction of labour. Babies born from obese mothers can be abnormally large (macrosomia) or small for gestational age, and have a higher risk of perinatal death and congenital malformation. Pregnancy induces marked and dynamic changes in energy metabolism, however, the direct effects of pregnancy adipose tissue biology in both normal lean and obese women is still largely unknown. The aim of this thesis was to delineate novel mechanisms by which pregnancy affects adipose tissue biology, and thus infer how obesity might adversely affect pregnancy outcomes. We used an animal model of obesity during pregnancy in which mice were given a high fat diet (HF) to make them obese. We identified that pregnancy was associated with an unexpected curtailment of visceral (mesenteric) adipose tissue mass in HF mice and with an attenuation, rather than worsening of the metabolic impairment expected from the combination of excess dietary fat and insulin resistance/glucose intolerance of pregnancy. To determine the underlying molecular mechanism contributing to this phenotype global gene expression microarray with subsequent pathway analysis and qRT-PCR validation was employed within the visceral adipose tissue. In visceral fat of HF pregnant mice, gene pathways for de novo lipogenesis and lipid storage, inflammation, retinol metabolism, insulin like growth factor and estrogenic signaling showed altered regulation. Given the known role of estrogen on adipose tissue and inflammatory cell function, a hypothesis was generated that altered estrogen receptor (ER)α expression/activation/increased estradiol presence within mesenteric fat formed a unifying molecular mechanism underlying the altered adipose biology and relative amelioration of the metabolic phenotype in HF pregnant mice. To test the ER α hypothesis, a female clonal adipocyte cell line, Chub-S7, and primary visceral and subcutaneous adipocytes from pregnant obese and lean patients were treated with the ERα selective agonist, PPT. PPT downregulated mRNA levels of key genes involved in de novo lipogenesis (ME1, FANS and SCD1 Dgat2), consistent with a direct role for ERα activation in curtailment of fat expansion. Although the primary human study lacked sufficient power to adequately address the hypothesis, PPT significantly suppressed SCD1 mRNA levels in visceral adipocytes of lean women. In parallel with the curtailment of mesenteric fat expansion, HF pregnant mice were found to have increased liver weight and liver triglyceride content. However, this “fatty liver” phenotype was not associated with increased mRNA levels of genes involved in hepatic triglyceride uptake or de novo lipogenesis. This increase in liver triglycerides may be due to an excessive influx of fatty acids from mesenteric fat through the portal vein. In conclusion, pregnancy in obese animals is associated with a beneficial curtailment in mesenteric fat expansion, normalization of metabolic disturbances and reduced adipose inflammation. Increased ERα activation within adipocytes may play a critical role in this phenotype.

During pregnancy glucose tolerance in the mother is affected. Glucose tolerance in pregnancy, as in the non-pregnant state is a continuum, represented by a distribution curve shifted to the right, with no clear divide between normal and abnormal. Many of the problems associated with overt diabetic pregnancies can be seen in infants of GDM pregnancies, such as macrosomia, neural tube defects, neonatal hypocalcemia, birth trauma and subsequent childhood and adolescent obesity. Impaired glucose intolerance (IGT) in pregnancy is also a major risk factor for the development of NIDDM (non-insulin dependent diabetes mellitus) and IGT in later life and is associated with not only an increased risk for coronary heart disease (CHD) disease but also many other morbidities and mortalities associated with overt diabetes. The problem remaining to be resolved is the precise level of glucose intolerance in pregnancy that poses a significant risk for the later health of the mother. Nor is increased gestational glucose intolerance the only reproductive event that has been linked with future NIDDM risk. Other factors have been known to predispose pregnant women to the risk of future diabetes (e.g. BMI, age and weight change). The findings of the present study suggest that the association of glucose intolerance during pregnancy, with the subsequent incidence of diabetes and certain co-morbidities in the mother, is continuous throughout the range of glucose concentrations studied. The risk of future diabetes is also affected by certain maternal characteristics (BMI at index pregnancy and at follow-up, weight change).

Objectives. The Pregnancy, Nutrition & Diabetes (PND) study aimed to evaluate the dietary status of urban Black pregnant women attending the Antenatal Clinic at the Charlotte Maxeke (Johannesburg General) Hospital. In addition, the study investigated the effects of maternal dietary intake and hormonal levels during pregnancy on fetal growth, birth size and the early postnatal development of risk factors for future Type 2 diabetes. The study analysis precedes a detailed description of the study population, including its comparison with other populations. Methods. 126 women were enrolled in the study before 24 weeks of gestation. Twice during pregnancy (weeks 20-24 and 30-36, visits V1 and V2) and approximately six months after the delivery (visit V3), volunteers participated in a standard 75 g oral glucose tolerance test (OGTT). Blood pressure, anthropometric and socio-demographic data were taken and a food frequency questionnaire was administered at each visit. The daily maternal intakes of total energy and macronutrients expressed as a % of total energy intake (%E) were calculated and further evaluated. A comparison with the crude nutrients intakes was also performed. During both pregnancy visits, an ultrasound examination was carried out to obtain estimates of fetal biometry and fetal well-being and the postnatal anthropometric parameters were also measured. Blood samples were collected at fasting, 30min, 60min and 120min of the OGTT for the measurements of maternal glucose (GLC), insulin (INS), C-peptide (C-PEP) and proinsulin (PI) and fasting samples for the determination of placental lactogen (HPL), insulinlike growth factor 1 (IGF-1), insulin-like growth factor binding protein 1 (IGF-BP1), free thyroxin (FT4), cortisol (CORT) and leptin (LEPT). Infant fasting blood samples were used for the analysis of the GLC, INS, PI, IGF-BP3 and LEPT. The plasma glucose samples were analysed on the Beckman Glucose Analyser 2, whilst all the other analytes were measured by an immunoassay method on 96-well plates. Results – DESCRIPTIVE DATA. Study participants. The majority of the study participants had completed high school education, however were unemployed and of low and very poor socio-economic levels. In comparison with another study from the developing world, the Pune study in India, the women from the current study were older, heavier with greater body mass index (BMI) and they were also taller. They had higher head and arm circumference. Birth outcomes. The birth size of African babies in the current study, although smaller in all parameters, was still relatively closer to the size of the Caucasian babies seen within the Southampton (Godfrey et al. 1996) or Helsinki (Forsén et al. 1997) studies than to the birth size of the babies from Trivandrum (Jaya et al. 1995) or Pune (Rao et al. 2001) in India. These relatively smaller African babies have comparable (or even larger) maternal placental sizes in relation to the mothers of both European studies. However, in comparison with the small Indian babies, the major difference noted was a substantially smaller placental size of the Pune mothers. Compared to z-scores from the World Health Organization (WHO) child growth standards (WHO Anthropo 2010), the PND study babies were born lighter and shorter with a larger head circumference (HC). A growth delay observed near the neonatal visit was followed by catch up growth in weight for age, however no catch-up growth was observed for length for age by the second postnatal visit. Dietary intakes. The PND study women had pregnancy energy intakes slightly below the national level intakes (Steyn et al. 2006), except for the energy intake at V3, which exceeded the national level. The lower energy intake during pregnancy is attributable to a lower intake of dietary protein and total carbohydrate. The fat intake was substantially higher in the PND study, with levels almost double at the second postnatal visit. This discrepancy may be due to differences between investigated populations or due to increased requirements of energy during lactation. In comparison with the Recommended Dietary Allowances (RDA), during the pregnancy period women in the current study had lesser crude protein and higher carbohydrate intake. Intake of the crude protein after delivery was low in comparison to the RDA for lactating women. Total carbohydrate intake exceeded the RDA. The relation between the intake of macronutrients expressed as a percentage of total energy (%E) and RDA was similar. The current study participants had a lower intake of energy, especially during the pregnancy period, when compared to populations in the developed world. They had a lower intake of protein at all visits in comparison with the national average for women or with that found in the Southampton study or when compared to the usual American diet. The energyadjusted intake of fat and carbohydrate were comparable with the Southampton and American data. This population in our study was therefore more comparable to that of Pune than to American or Southampton populations. However, despite similar total energy intakes as the Pune Study, total protein and fat intakes were higher in the African mothers, which may explain their higher weights and birthweights of their babies. Results – ANALYTICAL DATA Dietary intakes. Maternal dietary intakes showed significant effects on the fetal biometrical measurements, mainly involving the fetal head, femur length and the size of abdomen. The outcomes also show a significant relationship between maternal protein intake and baby’s birth weight. Associations were also found for maternal dietary intakes and the neonatal length and BMI and the markers of the infant β-cell function. Intakes of the plant protein and polyunsaturated fat supported the linear growth. There was no correlation between maternal dietary intake and the fetal growth rate. Effects of the total energy intake and carbohydrate seemed to be direct, while the effect of protein and fat may be delayed, possibly involving metabolic adaptation of the mother and the partitioning of nutrients between the mother, placenta and fetus. (See Table: Associations between the maternal dietary intake and the neonatal INSF1 levels, Pg. xiv). Maternal hormones. The data of the current study show significant relationships between maternal pregnancy hormones and fetal growth rate and the postnatal growth rate, although maternal anthropometry and fetal gender and BMI are also significantly involved. The maternal thyroid hormones seem to play an important role in fetal and postnatal growth and insulin metabolism (N=76, p=0.002, ß=-0.343; AR2=0.106) in the association with the neonatal fasting insulin. Discussion. The outcomes of the current study show that the African pregnant women in the study had lower energy intakes attributable to a lower intake of dietary protein and total carbohydrate. Maternal dietary intakes showed significant effects on the fetal biometrical parameters. Protein dietary intake was positively associated with baby’s birth weight and was shown to be statistically significant. Associations were also found for maternal dietary intakes and the infant postnatal BMI and the markers of the infant β-cell function. Quality of the protein and fat has different effects on fetal/infant growth. Maternal hormones showed correlations with fetal growth rate and the outcomes of the current study also show that maternal hormones can affect neonatal and early postnatal infant glucose levels and β-cell function. They are also linked to the programming of early obesity. The maternal thyroid hormones seem to play an important role. The maternal low energy, protein (especially plant protein) and PUFA intakes during gestation may be the reasons for the lower z-score birth parameters of the infants in comparison with the World Health Organization (WHO) child growth standards (WHO Anthro 2010). The disproportionally larger head of the newborn may be an outcome of the brain sparing effect. A suggestion for an increased maternal dietary intake of energy, protein and PUFA has been made.

Introduction The most tragic outcome of a teenage pregnancy is a teenage maternal death. Research from African countries has shown that pregnant teenagers are at increased risk for maternal death when compared with older women, chiefly from complications of hypertension in pregnancy and pregnancy-related sepsis. The objectives of this study were to determine the proportion of maternal deaths accounted for by teenagers, and to describe associated obstetric factors, causes of death and avoidable factors. Setting and methods This was a descriptive retrospective study, using records of all maternal deaths at Chris Hani Baragwanath Hospital (CHBH) from 1997 to 2011. All maternal deaths at CHBH are notified to the national government, and complete patient records have been kept since 1997. All teenage (age less than 20 years) maternal deaths were found by hand-searching all maternal death files for the study period. Demographic and obstetric details were recorded, as well as the primary cause of death and avoidable factors in each case, using the methodology of the Confidential Enquiries into Maternal Deaths in South Africa. Results There were 33 teenage maternal deaths out of a total of 562 deaths (6.1%). Eighteen (54.5%) of the teenagers were 18 or 19 years old. Nine died without having booked for antenatal care.Twenty-six (78.8%) were 28 weeks or more pregnant or postpartum when they died. The most frequent causes of death were hypertensive disorders of pregnancy (n=10; 30.3%), including 9 cases of eclampsia, and non-pregnancy-related infections (n=10; 30.3%), including 6 cases of lower respiratory tract infection and 2 foreign nationals who died of malaria. Among the teenagers who died from non-pregnancy-related infections, 3 were HIV infected, 4 were HIV negative and 3 did not have HIV results. Infrequent causes of death included pregnancy-related sepsis (n=2; 6.1%), and postpartum haemorrhage (n=1; 3.0%). The most frequent avoidable factors were failure to book for antenatal clinic (n=5; 15.2%) and delay in seeking medical help (n=8; 24.2%). Conclusion Maternal deaths in teenagers were infrequent and occurred in a lower proportion of all maternal deaths (6.1%) than expected, based on data suggesting a 13% teenage pregnancy proportion from a study done in 1999 to 2001. This finding differs from those in other African countries. The high frequency of eclampsia is similar to data from other countries, but pregnancy-related sepsis was not frequent. Development and maintenance of adolescent community resources and health services, including improving access to foreign teenagers, may improve health care utilisation by teenagers. Utilisation indicators would include use of contraception, uptake of termination of pregnancy services, and antenatal care attendance for ongoing pregnancies.

A research report submitted to the Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg In partial fulfillment for the requirement for the degree Master of Public Health 25 August 2014 / BACKGROUND Tuberculosis is the leading opportunistic infection among HIV-infected adults, including pregnant women, globally. Accurate screening tools are needed to identify those requiring further laboratory testing and to initiate isoniazid preventive therapy in a timely manner. This study determined the accuracy of symptom-based screening and in particular the performance of the WHO recommended TB symptom screening algorithm in HIV-infected pregnant women. METHODS A cross-sectional study was conducted among consenting HIV-infected pregnant women attending routine antenatal clinics in Matlosana, South Africa recruited >1 week after first HIV diagnosis between June 2010 and February 2011. Sputum was collected from all women followed by a systematic TB symptom screen. The performances of each symptom (cough, fever, weight loss and night sweats) alone and in combination were assessed with TB confirmed by sputa using microscopy and liquid culture (MGIT), as reference or gold standard. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were calculated for each of the four symptoms (cough, fever, weight loss and night sweats) and their combination. Logistic regression was carried out to find associations between patient characteristics and TB. RESULTS Overall, Mycobacteria Growth Indicator Tube (MGIT) confirmed prevalence of TB was 2.4% (35/1456) in this sample group. Only 11/38 (29%) women with confirmed TB reported any symptoms. Cough, fever, weight-loss and night sweats, individually and in combination had sensitivities ranging from 2.7-27% and specificities ranging from 84-97%. The positive predictive and negative predictive values for any symptoms of cough, fever, night sweats, or weight loss were 4.2% and 98%, respectively. TB was associated with decreasing CD4 count, close TB contact, cough, and night sweats. DISCUSSION The remarkable number of asymptomatic TB in HIV-infected patients, including in the cohort included in this study highlights the limitation of symptom-based screening. The low sensitivity of the symptom screen would incorrectly stratify patients who are being considered for Isoniazid Preventive Therapy (IPT). However, one could argue that the high negative predictive value of the symptom screen would justify its use in resource-limited settings as the initial step in identifying patients who should receive IPT. Although household TB and the father of the baby having TB were found not to have statistically significant associations with active TB, they are of public health importance as they play a role in the spread of the infection. CONCLUSION The WHO 4-symptom screen had low sensitive among HIV-infected pregnant women but negative predictive value was high. Few women with TB disease reported symptoms on direct questioning; the high rate of subclinical/ asymptomatic TB is concerning. There is an urgent need for more sensitive screening tools for TB in HIV-infected pregnant women

The placenta is responsible for mediating fetal growth and development, thereby influencing health across the lifespan. Physical activity (PA) confers benefits to mother and baby during pregnancy, but little is known about its impact on the placenta. There were two purposes of this study: i) to determine if maternal PA during pregnancy influences placenta mitochondrial protein content and function, and ii) to determine if there were differences in placenta mitochondrial protein content and function in different regions of the placenta, namely proximal or distal to the centre of the placenta. Healthy women between 12-28 weeks gestation were recruited, and free-living PA was objectively assessed at multiple time points during pregnancy using an accelerometer. Participants were grouped by minutes of moderate-to-vigorous PA (MVPA) per day. Placenta tissue samples were collected from central and distal placental regions immediately post-birth and were used for two separate analyses. Half of the samples were flash frozen in liquid nitrogen and used for western blot analysis of mitochondrial complex I-V proteins. Fresh mitochondria were isolated from the other half of the samples, and high-resolution respirometry was used to measure placental mitochondrial respiration. There were significant positive correlations between maternal PA and mitochondrial protein content in peripheral tissue samples, but protein content was significantly higher in central tissue compared to peripheral tissue samples. In addition, state 3 respiration was higher in central tissue samples of placentas from participants with high MVPA compared to participants with low MVPA. Finally, complex I protein was higher in central tissue samples of placentas from female offspring compared to placentas of male offspring. However, many of these results are underpowered and further study is warranted. This study provides new avenues to explore the relationship between PA and placenta mitochondria in healthy populations.

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Pregnancy loss, the demise of a pregnancy at any time between implantation and delivery, is a common event in women’s lives, affecting approximately one in three pregnancies. Pregnancy loss often causes profound psychological distress to women, their partners, and their families. However, despite its frequency and troubling nature, relatively little is known about the natural history of pregnancy loss, especially the multitude of signs and symptoms that precede a loss and distinguish it from an ongoing healthy pregnancy. One of the challenges in describing the natural history of pregnancy loss is that most losses occur very early, before entry to clinical care, necessitating the use of preconception cohort studies. Few such studies have ever been conducted worldwide. This dissertation aimed to describe the natural history of early pregnancy loss at <20 weeks gestation for the first time using a unique preconception cohort with daily prospective follow-up from the start of the pregnancy attempt through seven weeks post-conception. To accomplish this goal, three specific aims were undertaken. First, a systematic literature review was conducted to synthesize the existing literature on the relationships between the signs and symptoms and pregnancy loss. Two analytic aims were then undertaken to delineate thoroughly the relationships between prospectively ascertained signs and symptoms—namely, vaginal bleeding, lower abdominal cramping, nausea and vomiting (hereafter referred to as “signs and symptoms”)—and subsequent early pregnancy loss. The first analytic aim used a fixed covariate and fixed effect survival analytic approach to estimate the cumulative incidence of early pregnancy loss by the presence of individual, combinations, and patterns of signs and symptoms and the associations between signs and symptoms and the cumulative incidence of pregnancy loss. The second analytic aim used a time-varying covariate and time-varying effect survival analytic approach to estimate the weekly associations between signs and symptoms and pregnancy loss to determine if these relationships were consistent or divergent across gestational ages. The results of the first and second analytic aims were then compared to gain a more complete understanding of the natural history of early pregnancy loss. The literature review revealed a dearth of studies on the signs and symptoms of pregnancy loss. Two preconception and 16 pregnancy cohort studies were identified. The literature suggested that vaginal bleeding, particularly heavy vaginal bleeding, was associated with an increased risk of pregnancy loss while vomiting, and in some studies nausea, was associated with a decreased risk of pregnancy loss. However, reliance on care-seeking cohorts, maternal retrospective reports of signs and symptoms after pregnancy loss, and retrospective recall of signs and symptoms over long periods (e.g., entire trimesters) may have biased the observed associations between signs and symptoms and pregnancy loss leading to incorrect inferences regarding the relationships between signs and symptoms and pregnancy loss. The two analytic aims addressed the data gaps identified in the literature review. The preconception cohort design with prospective daily follow-up from the beginning of the pregnancy attempt facilitated the ascertainment of pregnancies at the earliest stages of gestation and losses prior to clinical care entry through the use of urine-based home pregnancy testing. The daily reporting of multiple signs and symptoms in the first five weeks after a positive home pregnancy test, or approximately two to seven weeks post-conception, allowed for a full description of the relationships between signs and symptoms of pregnancy loss without recall bias. Data for the two analytic aims come from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, a population-based cohort with preconception recruitment of couples in 16 counties in Michigan and Texas followed for 12 months of trying for pregnancy and then through pregnancy loss or delivery for couples achieving an hCG pregnancy. 501 couples entered the study, and 347 achieved a pregnancy during the study period. Three hundred forty-one singleton pregnancies comprise the study population for the two analytic aims in this dissertation. Overall, 95 (28%) pregnancies in the study population ended in a pregnancy loss. Lower abdominal cramping, nausea, and vomiting were often reported during the early pregnancy period; vaginal bleeding was less common. The results of the fixed covariate fixed effect survival analysis from the first analytic aim demonstrated that vaginal bleeding, particularly heavy bleeding and bleeding accompanied by lower abdominal cramping, was associated with an increased risk of pregnancy loss. In contrast, the presence of vomiting, but not nausea alone, during the early pregnancy period was associated with a lower risk of loss. Analyses in the second analytic aim using weekly time-varying covariates and time-varying effects of signs and symptoms on pregnancy loss revealed some new findings. The first week after a positive pregnancy test appeared to be a vulnerable period. Vaginal bleeding and lower abdominal cramping were associated with an increased risk of loss in the first week but not in later weeks; conversely, nausea and/or vomiting were associated with lower risk of pregnancy loss but only after the first week. The observed weekly variations in the signs and symptoms of pregnancy loss may reflect changes in maternal adaptation to pregnancy across gestation. Overall, relatively little is known about the biological processes underlying healthy and unhealthy adaption to pregnancy as well as how embryo quality may affect these adaptive processes. More work is required from basic scientists, clinicians and epidemiologists to better understand the causes of signs and symptoms and their relationships to pregnancy loss, including genetic and environmental factors and their interactions. In the meantime, prognostic models developed from data in this dissertation using time-varying signs and symptoms may be useful to women and their health care providers for identifying pregnancies at increased risk for pregnancy loss. These models could prompt women to seek medical care when concerning patterns of signs and symptoms arise.